Numistify guide
How to Spot Fake Coins: A Practical Guide
Counterfeit coins target exactly what people want most: key dates, silver dollars and gold. A few simple checks catch the crude fakes; the good ones need a professional. Here is how to tell which is which.
The short answer
Check the weight and diameter against the official specifications, test the coin with a magnet, look at the edge for a casting seam and inspect the date and mint mark under magnification. Passing these tests does not prove a coin genuine — a tungsten-core gold fake can match both weight and size — so have valuable coins authenticated by a grading service.
The kinds of fake
Counterfeits are coins the mint never made. Some are cast in a mould; better ones are struck from copied dies, including dies made by transferring the design from a genuine coin.
Altered coins are genuine coins changed to look rarer, usually by adding a mint mark or changing a date.
The targets are predictable: key dates, Morgan dollars and other silver, gold coins and modern bullion.
Simple checks anyone can do
Weight. Genuine coins are made to precise weights; a Morgan dollar, for example, weighs 26.73 g. Use a scale accurate to a hundredth of a gram and compare with the official specification for that coin.
Diameter and thickness. A counterfeiter using a cheaper metal who matches the weight usually ends up with a coin that is too thick or too wide. Digital calipers show it.
The magnet. Silver, gold and copper are not magnetic. A “silver” coin that sticks to a strong magnet has iron or steel in it and is fake.
The ring. Genuine silver and gold give a clear, lasting ring when gently tapped, where many fakes sound dull. Be careful not to mark a high-grade coin.
The edge. A thin seam running around the middle of the edge is a sign of a coin cast in two halves.
Repeated marks. If several coins of the same date show the identical tiny mark in the same place, they were probably struck from the same copied die.
What the tests cannot prove
These checks catch crude fakes, but passing them does not prove a coin genuine. Many counterfeit metals — tungsten, lead, copper — are not magnetic. Fake gold coins with a tungsten core can match the weight and size of the real thing. And a few genuine coins are magnetic by design, such as the US 1943 steel cent. Treat the tests as a way to rule coins out, not to rule them in.
Altered dates and mint marks
The most common alterations turn a common coin into a key date: a D added to a 1916 Mercury dime to imitate the scarce 1916-D; an S and the designer’s initials VDB added to a 1909 cent; a 1917 Standing Liberty quarter tooled to read 1916. Under magnification, an added mint mark often shows a seam, tool marks or a texture that does not match the rest of the coin. Compare with photographs of genuine examples, such as those in PCGS CoinFacts.
Fake grading holders
Counterfeiters also fake the sealed holders of the grading services. Before trusting a graded coin, look up its certification number on the PCGS or NGC website and check that the coin, grade and photograph on record match the one in your hand.
Buying safely
For key dates, gold and anything whose loss would hurt, buy coins certified by PCGS or NGC from reputable sellers, and check the certificate. Be wary of prices far below the market. For a coin you already own, show it to your local coin shop, or have it authenticated by a grading service; our guide to sending coins for grading explains how.
Questions people ask
How can I tell if a coin is fake?
Check its weight and diameter against the official specifications, test it with a magnet, look at the edge for a casting seam and inspect the date and mint mark under magnification. If anything is off, or the coin is valuable, have it authenticated by a grading service.
Are silver coins magnetic?
No. Silver, gold and copper are not magnetic, so a silver coin that sticks to a magnet is fake. But passing the test proves nothing, because many counterfeit metals are not magnetic either.
Can a fake coin weigh the same as a real one?
Yes. Fake gold coins made with a tungsten core can match both the weight and the size of the genuine coin, which is why weight alone cannot prove a gold coin genuine.
What is an altered coin?
A genuine coin changed to look like a rarer one — for example a common 1916 Mercury dime with a D mint mark added to imitate the scarce 1916-D, or a date tooled from 1917 to 1916.
Can graded coin holders be faked?
Yes. Counterfeit holders exist. Check the certification number on the grading service’s own website and compare the coin with the photograph and details on record.
Related guides
Key date coins — the coins counterfeiters target most.
Where is the mint mark? — where it should be on genuine coins.
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